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RESEARCH PRODUCT

Familial seborrhoeic keratosis associated with multiple 'pure reticulated acanthomas' and infundibulocystic basal cell carcinomas.

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Background A variety of genodermatoses with multiple cutaneous tumors with germline genetic alterations such as Gorlin syndrome with PTCH1 gene mutations have been described. Other cutaneous syndromes have been associated with somatic gene mutations, such as FGFR3 in familial seborrhoeic keratosis. Objective We describe the clinical, dermoscopic, and histopathological features of multiple cutaneous lesions, mostly infundibulocystic basal cell carcinomas and pure reticulated acanthomas, present in a family affected by familial seborrhoeic keratosis. In addition, we tested for possible germline alterations in the FGFR3 and PTCH1 genes. Methods Ten members of one family were clinically examined. Ninety-two skin biopsy specimens were evaluated. Blood samples from six subjects were analyzed for FGFR3 and PTCH1 germline alterations. We review the literature concerning genetic FGFR3 alterations in seborrhoeic keratosis. Results Subjects of all generations affected by familial seborrhoeic keratosis also presented other skin tumors which corresponded histologically to reticulated acanthomas without apocrine or sebaceous differentiation as well as infundibulocystic basal cell carcinomas. In addition, two novel germline variants, p.Pro449Ser (c.1345C>T) in FGFR3 gene and p.Pro725Ser (c.2173C>T) in exon 14 of PTCH1 gene were identified in five subjects. Conclusion We characterize for the first time the clinical, dermoscopic and histopathological features of multiple reticulated acanthomas without apocrine or sebaceous differentiation, for which we propose the term “pure reticulated acanthoma”, and infundibulocystic basal cell carcinomas, associated with familial seborrhoeic keratosis. We identified FGFR3 and PTCH1 germline polymorphisms whose influence in the development of reticulated acanthomas is unknown. This article is protected by copyright. All rights reserved.